200 g of $20 \% \mathrm{w} / \mathrm{w}$ urea solution is mixed with 400 g of $40 \% \mathrm{w} /…
200 g of $20 \% \mathrm{w} / \mathrm{w}$ urea solution is mixed with 400 g of $40 \% \mathrm{w} / \mathrm{w}$ urea solution. What is the weight percentage (w/w \%) of resultant solution?
30.33
33.33
36.33
28.33
Solution
200 g of $20 \%$ urea contain 40 g urea in 200 g solution
400 g of $40 \%$ urea contain 160 g urea in 400 g solution.
Total amount of solution $=600 \mathrm{~g}$
Total amount of urea in solution $=200 \mathrm{~g}$
Hence,
Weight $\%$ of urea in solution $=\frac{200}{600} \times 100$
$=33.33 \%$